The Institute of Electrical and Electronics Engineers Inc. (IEEE) 802.11ac which achieves a higher data rate in IEEE 802.11 which is a wireless local area network (LAN) standard is developed by the IEEE. Currently, standardization of IEEE 802.11ax is started as the succeeding standard of IEEE 802.11ac. As wireless LAN devices have been propagated rapidly, even in the standardization of IEEE 802.11ax, the improvement of throughput for each user in an environment has been examined in which the wireless LAN devices are overcrowded.
The wireless LAN device monitors a preamble defined in IEEE 802.11, and demodulates a physical layer convergence protocol (PLCP) header or a data signal in a case where the preamble is detected. For example, as the preamble defined in IEEE 802.11, there are legacy-short training sequence (L-STF) and legacy-long training sequence (L-LTF). An operation needed to demodulate a data signal such as synchronization or channel estimation may be performed by using these preambles.
The wireless LAN device detects the preamble, and then receives the PLCP header. The PLCP header includes information (modulation and coding scheme (MCS) or the like) needed to demodulate the data signal subsequent thereto. PLCP headers are differently defined depending on the types of the IEEE 802.11 standards such as a high throughput-signal (HT-SIG) defined in IEEE 802.11n and a very high throughput-signal (VHT-SIG) defined in IEEE 802.11ac. Meanwhile, as a mechanism for protecting a terminal apparatus (legacy terminal apparatus) corresponding to the conventional standard (IEEE 802.11a/b/g or the like), legacy-signal (L-SIG) is generally inserted after L-LTF.
For example, the L-SIG may include information regarding a signal transmission period of a transmission frame including the L-SIG. The wireless LAN device that receives the L-SIG including the information regarding the signal transmission period may acquire information for configuring a network allocation vector (NAV) without receiving the data signal subsequent to the L-SIG.
As stated above, since the preamble and the PLCP header include various information items such as information regarding the signal transmission period or the demodulation of the data signal, the wireless LAN device needs to detect the preamble and the PLCP header with high accuracy.